There is nothing from/for the router on the computers installed (which is not there anyway).
All you do is to buy the new router. Then you have to configure the new router once and afterwards it does work. I would not even recommend to use the program on the cd for the configuration but rather go through the web configuration interface at http://192.168.1.1/ Just write down all the current settings of the g router. Then setup the n router with the same settings (except for the wireless bands to use unless you want to use the n router for g connections only).
If you use the same wireless network name (SSID) and the same wireless security settings on both routers then you won't have to make any changes on the computers. They will connect to the new router just as they did to the old one.